j -- Join command

               default range           syntax
                         ^,.           j[/string[/]]

        "j"  is used to join the specified lines into a single line.
        If "string" is present, it is inserted between each pair  of
        lines  joined.  If not, a single blank is used.  "j/" is the
        same "j//", i.e., no string at all will be inserted  between
        the  joined  lines.   The  "/"  may  be  any character.  The
        trailing delimiter is optional.

        To return to the command directory, type "hcomdir."